I am quite sure continuous focus, AF-C, consumes a bit more power, so turn that off. Also, it is worth noting that the EXR Auto mode forces AF-C, so in situations where battery consumption is a concern and you want to make use of EXR, chose you EXR mode, but not the EXR Auto mode.

And again having the LCD turned on with preview will also consume more power than simply looking through the "passive" OVF...